[Tests] Update to new Makefile.plugin setup

- Declare explicitely the presence of tests/print.ml
- Compile it as dependency of `ptest_config` rather than
  `E_ACSL_TESTS` (in the latter case, they might not be compiled when
  `ptests` is launched, because `ptests` is launched by
  `E_ACSL_DEFAULT_TESTS` which is itself a dependency of `E_ACSL_TESTS`).

src/plugins/e-acsl/Makefile.in

@@ -117,8 +117,11 @@ $(PLUGIN_DIR)/tests/print.cmo: BFLAGS=-I $(FRAMAC_LIB) -I tests
 $(PLUGIN_DIR)/tests/print.cmx: OFLAGS=-I $(FRAMAC_LIB) -I tests
 
 PLUGIN_TESTS_DIRS := reject runtime bts gmp no-main
+PLUGIN_TESTS_LIB:=tests/print.ml
 
-E_ACSL_TESTS: $(PLUGIN_DIR)/tests/test_config \
+E_ACSL_TESTS: $(PLUGIN_DIR)/tests/test_config
+
+$(PLUGIN_DIR)/tests/ptests_config: \
 	$(PLUGIN_DIR)/tests/print.cmxs \
 	$(PLUGIN_DIR)/tests/print.cmo